Memory

Question 1

What are the best RAM slots to use for dual channel memory with four slots?

Answer 1

A2 and B2 (or 2 and 4)

Question 2

What is asymmetric dual channel mode?

Answer 2

For example, you have 4GB and 8GB. The lower half of the 8GB and the 4GB run in dual channel mode and the top half of the 8GB runs in single channel mode

Question 3

What are the differences between single channel and dual channel?

Answer 3

At the same total channel size, Dual channel is slightly faster than single channel and allows you to get your RAM cheaper (for example, 16GB vs 8GB+8GB)

Question 4

What hardware components need to support multi-channel for it to work?

Answer 4

The motherboard and the CPU

Question 5

What is a common size per channel for multichannel motherboards (in bits)?

Answer 5

Often each channel is a 64-bit channel

Question 6

What is the difference between MHz and MT/s in RAM speeds?

Answer 6

MHz is a million cycles per second. MT/s is a million transfers per second. Because DDR RAM completes 2 cycles per second, the MT/s rate is the effective MHz. In DDR RAM, the effective frequency (twice the base frequency) is equal to the data transfer rate.

Question 7

How do you get from Transfers/s to Bytes/s?

Answer 7

Data is transferred 64 bits at a time (with 64-bit architecture), divided by 8 bits per byte. So the Transfers/second or the effective frequency is multiplied by 8 as each transfer constitutes 8 bytes.

Question 8

What does DDRX-XXXX represent?

Answer 8

The type and transfer rate of the chips on a memory module in MT/s (Million Transfers per second) or effective cycles/second (effective MHz). The Base speed is 1/2 the effective speed.

Question 9

What does PCX-XXXX represent?

Answer 9

The type and transfer rate of the module in MB/s

Question 10

What is the difference between SIMM and DIMM?

Answer 10

SIMM is 32 bit and DIMM is 64 bit. They are two form factors

Question 11

How many pins does DDR memory have?

Answer 11

184

Question 12

How many pins does DDR2 have?

Answer 12

240

Question 13

How many pins does DDR3 have?

Answer 13

240

Question 14

How many pins does DDR4 have (DIMM and SODIMM)?

Answer 14

288 DIMM

260 SODIMM

Question 15

What is SRAM?

Answer 15

Static Random access Memory: generally used in CPU caching. Faster and more expensive, doesn’t need voltage to retain data

Question 16

What are the common types of DRAM?

Answer 16

DRAM, SDRAM (includes SDRAM, DDR, DDR2, DDR3, and DDR4)

Question 17

What is SODIMM?

Answer 17

Small Outline dual inline memory module (laptop form factor)

Question 18

Are DDR memory standards backwards compatible (DDR, DDR2, DDR3, DDR4)?

Answer 18

No

Question 19

What are the voltages of different types of DDR RAM?

Answer 19

DDR: 2.5/2.6 V
DDR2: 1.8 V
DDR3: 1.35/1.5 V
DDR4: 1.2 V

Question 20

Does the FSB (Front Side Bus) Frequency Capacity limit the speed of RAM?

Answer 20

Yes - if the RAM frequency is higher than the Front Side Bus it will lower the speed to match the frequency of the Front Side Bus

Question 21

What is the range of transfer rate in GB/S for DDR4?

Answer 21

Ranges from 19.2 GB/s to 35.2 GB/s

Question 22

What is the range of Transfers/s for DDR4 RAM?

Answer 22

Ranges from 2.4 GT/s to 4.4 GT/s (or 2400 MT/s to 4400 MT/s)

Question 23

What is ECC RAM?

Answer 23

It is a type of RAM that detects and corrects errors or integrity issues. Typically more expensive, slower, and used in commercial applications or servers. Non-ECC is more common. Motherboard and CPU will need to be able to support it and often requires higher-end Motherboards and CPU

Question 24

What is the benefit of getting RAM with parity?

Answer 24

Parity detects and discards errors without correction.

Question 25

What is buffered vs unbuffered RAM? (Also known as registered vs unregistered)

Answer 25

Adds a “buffer” (extra chip) on the RAM module that provides extra stability. Expensive, slower, often used in servers. Motherboard and CPU will need to be able to support it and often requires higher-end Motherboards and CPU

Question 26

What does SO-DIMM stand for?

Answer 26

It stands for “Small Outline - Dual Inline Memory Module

Question 27

What does CL Latency (or CAS Latency) stand for?

Answer 27

Column Address Strobe Latency

Measures nanoseconds of latency

Question 28

What is RDIMM?

Answer 28

Registered Dual Inline Memory Module (registered or buffered memory) - opposite of UDIMM

Question 29

What is LRDIMM?

Answer 29

Load Reduced Dual Inline Memory Module - adds buffer both to chips and data lines which produces even better performance than RDIMM’s at very high memory amounts such as 256 GB or 512 GB. Not compatible with RDIMM’s

Question 30

What does a memory riser do?

Answer 30

Adds additional RAM slots to increase RAM slot capacity. Does not increase overall memory capacity of motherboard

Question 31

What is x4, x8, x16 in reference to memory specification?

Answer 31

It references the number of bits each physical chip can transfer at one time. For each rank of memory, on an x64 processor, x4 chips require 16 chips per rank, x8 chips require 8 chips per rank, and x16 chips require 4 chips per rank

Question 32

What is a memory rank?

Answer 32

A data block that is 64 bits wide. Each memory rank is comparable to one “normal” stick of memory. RAM slots have individual limits for number of ranks, and motherboards have limits for overall number of ranks

Question 33

What is UDIMM?

Answer 33

Unbuffered Dual Inline Memory Module - opposite of RDIMM